hong kong people vs chinese people

I like the part from answer #2, 而加回歸咗, hong kong人咪開始刷鞋.
Adding to that, Hong Kong people are strong survivors meaning they are able to adopt to rapidly changing environments. That ability alone set them apart from some mainland Chinese who can be more idealistic (partly due to communist influence and more traditional value).

A short list of history events (beside the ones already mentioned in the two previous replies) that cause such discrimination:
1. Hong Kong 1956 riots
2. Hong Kong 1967 Leftist Riots
3. Rapid economic growth in Hong Kong during 1970s while mainland China was still way behind
4. Popular spread of discrimination against mainland Chinese in mid-to late 1970s (see TV show 親情 (電視劇) for example)
5. The long period of fear (1980s to 1990s) on Hong Kong's return to China rule

Because Hong Kong people live in an advanced civilization, and the people in China are kind of fall behind them. 可以話係睇小人啦! 因為中國d人比較窮, 所以冇乜讀書, 因此知識方面就比較小, 唔識人情世故, 而且以前重係共產黨, 咁樣咪比hong kong人話唔識趣同鄉下囉! 而加回歸咗, hong kong人咪開始刷鞋, 乜都話中國好, 同支持中國. 你話人類係唔係好現實呢!

i guess you better clarify your questions a little bit first.... it doesn't make sense ....

are you trying to ask why hong kong people don't like those who are from mainland china?

I think it's mainly due to cultural differences and habits........Many HK people think they're rude and always do embarrassing things...